Barhandar
You can input that manually. Also, you need to provide the browser - mine does save the input on navigation, and even on closing and reopening the tab.
(twi|pony)booru.org
- (E) The Derpibooru editor is unique, it does not follow a common convention (like markdown), so using an external editor means missing on the rich text support provided by the editor (for spoilers, code, links, images, etc.).
You can input that manually. Also, you need to provide the browser - mine does save the input on navigation, and even on closing and reopening the tab.